The present invention relates generally to endodontic posts and pins and more specifically to endodontic posts and pins fabricated of fiber reinforced composite material.
Conventional endodontic posts are typically fabricated of metals or metal alloys. The metallic posts fabricated of less noble alloys can cause electro-chemical corrosion and weaken the restoration. In the natural tooth, the elastic modulus of dentin in the crown portion is about 20 GPa, and at root portion is about 9 to 10 GPa. The mismatch of the elastic moduli of metallic post and dentin very often initiates dentine fracture, especially at the apex of the root. Additionally, many conventional dowel pins are threaded and must be screwed into dentin. This can also increase the potential for weakening and eventual fracture of the tooth.
There is a need to provide aesthetically pleasing posts and pins. It is desirable that the posts and pins are rigid and strong to support the stresses occurring in the mouth. It is important that the posts and pins are compatible with the properties of the endodontic materials in the mouth.
These and other objects and advantages are accomplished by the post and pins of the present invention comprising a rod fabricated of fiber-reinforced composite material. The rod comprises a plurality of frustoconical sections arranged coaxially along the longitudinal axis of the rod. Preferably the rod has consistent width along the longititudinal axis wherein the frustoconical sections each have the same tapered width and same length. The number of frustoconical units per rod can vary. The frustoconical sections may vary in shape. Moreover, the rod may include a channel therein extending along the longitudinal axis thereof. The rod may also include one or more grooves or flat surfaces extending along the surface thereof. In another embodiment, the post may include a portion of fibers or alternatively, all of the fibers, that are either pigmented or inherently colored to enable identification of the post inside the mouth.
The material formulation and surface design of the post of the invention are beneficial because the matrix resin of the post, filling material between the post and the root canal, and the core material disposed on top of the post, all contain the same or very similar chemical components. This enables better chemical bonding of the system. Furthermore, the rough surface structures of the post promote chemical bonding as well as mechanical anchors, resulting in a better retention of the post.